A portion of any certification program is the awareness of the inherent dangers of thermography and the techniques and skills needed to ensure safety in the workplace. Common sense dictates much of what constitutes safe work practice, but special precautions often apply to a specific application. For example, thermographers who inspect electrical systems may have a greater exposure to the potential of an arc blast.
In many instances, they are inspecting energized equipment which, immediately after the enclosure has been opened, can trigger a phase-to-phase or phase-to-ground arc. An arc flash is an extremely high-temperature discharge produced by an electrical fault in the air—and FYI, arc flash temperatures can reach 35,000oF (19,427oC)! An arc blast is an explosion that occurs when air surrounding electrical equipment becomes ionized and conductive. The threat of an arc blast is greatest for electrical systems of 480 V and higher.
A flash protection boundary is the distance at which personal protective equipment (PPE) is required for the prevention of burns when an arc flash occurs (See Figure 1). While a circuit that is being repaired should always be de-energized, the possibility exists that nearby circuits are still energized within the flash protection boundary. Therefore, barriers, such as insulation blankets, along with the proper PPE, must be used to protect against an arc flash. However, the consequences of an arc blast are often deadly and extensive—so safety must always be practiced!
While the risk for an arc blast is minimized by not opening the cover or door to an enclosure, this also eliminates most of the benefit of thermography, as we cannot see through the enclosure covers (See Figure 2). However, many enclosures are now installed with special infrared transparent windows or viewports, and these features can reduce the risk of arcing to yield good, solid results.
When enclosures must be opened, procedures should be carefully developed, implemented, and followed that will minimize the risk of an arc flash. National Fire Protection Agency (NFPA) 70E is one of several standards that can be useful when developing such procedures.
Routine electrical inspection can be much safer and more effective when conducted by a team. The team could consist of two people, such as the thermographer and the qualified person who opens enclosures, measures loads, and safely closes the enclosure once work has been completed. A qualified person is one who has the knowledge and skills related to the construction and operations of electrical equipment, and, of course, have received appropriate safety training.
Work for building inspections is typically less risky. However, risks do exists—such as, when accessing crawlspaces and attics. Care must also be taken when being exposed to construction work that is in progress.
Thermographers working in any industrial environment must always be aware of other hazards, including the potential for trips and falls, and enclosed-space entry hazards. Bright clothing may also be required in many environments. On roofs, precaution must be taken for fall hazards, not only at the roof edge but also for simple changes in elevation or over a structurally weakened roof deck. Work performed on roofs should never be performed alone!
Furthermore, special precautions must be taken at night. A thermographer can become night blind when viewing a thermal image in the bright display of an imaging system. Night blindness is a condition that occurs when a thermographer’s eyes adjust to view a brightly lit display screen and, as a result, are not adjusted to see a dark object.
Accidents typically occur when work is not planned or when the nature of the planned work changes—but the plan does not. A safe-work plan should always be developed and followed. When circumstances change, the plan must be reevaluated for any necessary changes.
The Occupational Safety and Health Administration (OSHA) is a United States government agency established under the Occupational Safety and Health Act of 1970 that requires employers to provide a safe environment for their employees. For example, OSHA requires that work areas must be free from hazards that are likely to cause serious harm. OSHA provisions are enforced by the U.S. government and safe-work plans can be developed within OSHA guidelines.
You have your certification; you have your safety standards and tips; now get out there and point & shoot—safely!